Grinding machines for machining workpieces are generally known in the art. Also centerless grinding machines as such are known in the art, particularly centerless cylindrical grinding machines. Centerless cylindrical grinding machines may be for instance arranged as external cylindrical grinding machines or internal cylindrical grinding machines. Generally, centerless grinding machines may be utilized for machining round, cylindrical workpieces, and exemplarily rotationally symmetric workpieces. Centerless grinding machines may be used for plunge grinding or for through-feed grinding, for instance.
Centerless grinding machines are particularly suited for series production and for mass production. Centerless grinding machines typically comprise a grinding wheel and a regulating wheel, wherein both the grinding wheel and the regulating wheel may be driven for rotation. The grinding wheel and the regulating wheel are generally arranged in a fashion parallel to one another and arranged to receive a to-be-machined workpiece therebetween. Generally, the grinding wheel comprises an abrasive material or is coated with an abrasive material. Generally, an abrasive material may be referred to as a material that is abrasively effective. The regulating wheel may comprise rubber material, rubber-like material and/or may be coated with rubber material and/or rubber-like material. In the alternative, the regulating wheel may comprise ceramic material and/or may be coated with ceramic materials
Generally, centerless grinding machines further comprise a workpiece mount which serves as a support for the workpiece. When the centerless grinding machine is operated for grinding, the workpiece may be thus contacted by the grinding wheel, by the regulating wheel, and by the workpiece mount. Regularly, the grinding wheel and the regulating wheel may be arranged in a fashion parallel to one another. It may be however also envisaged to arrange the grinding wheel at a small angular offset with respect to the regulating wheel. In this way, a feed movement for the workpiece may be generated.
Frequently, the grinding wheel comprises a greater diameter than the regulating wheel. The grinding wheel and the regulating wheel are generally provided with drives and/or may be coupled with drives. Generally, the grinding wheel and the regulating wheel are driven in the same direction of rotation, wherein, however, the respective drives are controlled in such a way that a circumferential velocity of the grinding wheel deviates from a circumferential velocity of the regulating wheel. As the workpiece is engaged, in the course of the grinding procedure, by the grinding wheel as well as by the regulating wheel which are generally operated at the same rotation direction, the workpiece is set in rotation due to the cooperation of the grinding wheel and the regulating wheel, wherein a direction of rotation is opposite to the direction of rotation of the grinding wheel and the regulating wheel, respectively. Due to the different circumferential velocities of the grinding wheel and the regulating wheel, a relative motion between the workpiece and the grinding wheel may be generated which may comprise slippage or spin. In this way, material may be removed from the workpiece.
When grinding at a grinding machine, particularly at a centerless cylindrical grinding machine, for instance a centerless external cylindrical grinding machine, regularly dynamic forces are generated that are based on dynamic effects. The dynamic forces may have an adverse impact on the grinding operation, particularly on the accuracy. In this way, particularly the dynamic compliancy (sometimes referred to as elastic modulus) of the grinding machine or of components thereof, may be impaired or mitigated. This may involve occurrences of dominant dynamic compliances. As a result, for instance rattling may occur. As used herein, the term compliancy may basically correspond to an opposite or even inverse of stiffness. The term compliance may be also referred to as resilience, at least in some exemplary embodiments. A reduced dynamic stiffness and/or dominant dynamic compliances may cause an increased wear of the grinding wheel and/or the regulating wheel and may cause a decreased quality of the workpiece. Particularly, the accuracy of the machining operation may be impaired. Further, particularly in case of resonance, increased stresses at components of the grinding machine may occur which may for instance have an adverse effect on bearings, guides, drives, and such like.
Measures for eliminating dynamic weak spots, particularly for preventing excessive dynamic compliances are generally known in the art. This may, on the one hand, for instance involve a general structural design of the grinding machine. It may be further envisaged to adjust grinding parameters to eliminate and/or exclude adverse dynamic effects. Grinding parameters may involve grinding materials, geometries of the grinding wheel and/or the regulating wheel, driving parameters (speed of rotation and/or circumferential velocity of the grinding wheel and/or the regulating wheel), infeed forces and such like. Structural design changes of the grinding machine and/or a corresponding structural machine design of the grinding machine is for instance recommendable when the grinding machine is basically used as a single-purpose machine.
However, further applications may be envisaged which are not feasible at all or only feasible at considerably increased effort on the basis of conventional approaches to the reduction of dynamic compliancy and/or to the elimination of dynamic weak spots.
Furthermore, conventional systems for influencing and/or damping the vibratory behavior of grinding machines are known in the art. These systems may be for instance, arranged as active damping systems and/or as passive damping systems. Active damping systems generally comprise at least one actuator which may be controlled in dependency of at least one detected value that represents the vibratory behavior of the grinding machine. Hence, active damping systems are frequently only feasible at huge effort, as a corresponding control system, sensors and respective actuators need to be provided. Passive damping systems may for instance comprise mass-spring systems which are provided at the side of a frame, and which are, in accordance with an exemplary embodiment, intended to influence the damping behavior of the grinding machine in an advantageous fashion. However, experience has shown that merely on the basis of such conventional systems at least for some applications no sufficient optimization of the vibratory behavior of the grinding machine may be achieved.
In view of this, it is an object of the present disclosure to provide a damping device for a spindle of a grinding machine, which permits an efficient damping of vibrations and an efficient reduction of dynamic compliances (dynamic resiliency) of the spindle.
It is a further object to provide a damping device which is particularly suited for a grinding spindle or regulator spindle of a centerless grinding machine.
It is another object to provide a damping device which may be implemented at moderate effort. Preferably, in accordance with this aspect, the damping device is suited for upgrading grinding machines that are already in operation, particularly respective centerless grinding machines.
It is a further object to provide a damping device which may contribute to an increase of the lifetime of the grinding machine, particularly of the grinding spindle or the regulator spindle and of the corresponding spindle drives, respectively.
It is still a further object to provide a damping device which may improve the general accuracy of the grinding operation.
It is yet a further object to provide a damping device may be adapted to an actual present application and operation type at moderate effort.
It is yet an even further object to provide a damping device that provides improved broad-band damping capabilities.
It is yet still a further object to provide a spindle which is provided with a respective damping device
It is yet still a further object to provide a grinding machine which comprises at least one of a grinding spindle and a regulator spindle including a corresponding damping device.